1. Field of the Invention
The instant invention is directed to an adhesive for sealing EPDM sheet. More particularly, the instant invention is directed to a two-component adhesive, chemically separated by a film which, upon heating, comes together to produce an adhesive effective to seal EPDM sheeting.
2. Background of the Invention
The increasing use of single-ply membranes, especially as roof coverings, has emphasized the need for development of excellent adhesives to seal seams to provide the same excellent leak-proof protection provided by the membranes themselves. The material of choice, and the roofing membrane enjoying the largest share in this market, is ethylenepropylene diene rubber (EPDM). Because of the resistance and inherent difficulties in employing more than a one-component system, the adhesive of choice in sealing this vulcanized EPDM sheet has been a chloroprene elastomer, i.e., neoprene, formulated in a suitable solvent. This one-component system relies on the inherent modulus and tensile properties associated with chloroprene. This adhesive does not provide the strength obtained by a vulcanizable product.
The one-component system of the prior art also, in common with many known adhesive systems, is characterized by the presence of an organic solvent. The presence of organic solvents increases the danger of combustion or explosion. In addition, the toxicity and environmental problems associated with solvents are well known.
As mentioned above, roofing installers resist the use of a two-component system which requires exact mixing of the two components. Moreoever, expensive losses of activated cements are incurred due to the short pot lives of these materials. It is true that expensive two-component systems have been developed. These packaged systems, for example, so-called "Bi-Packs", are special coaxial cartridges, which mix a premeasured amount of sealant as required for on-site application and are characterized by their high price.
A two-component adhesive for EPDM sheet is disclosed in the art. Flory, et al., Ind. Eng. Chem, Vol. 38, 500 (1964), discloses the use of a combination of p-quinone dioxime and lead dioxide as an ambient curing agent for EDPM. Cantor, Adhesive Age, June, 1974, teaches a two-component adhesive comprising p-quinone dioxime and an organic oxidant.